Heretofore, methods of producing unsaturated carbonyl compounds using acetylene compounds as starting materials have been widely known. For instance, a method using a Pd compound containing a small amount of an organic phosphine as a catalyst, and a method of utilizing a soluble salt of a metal belonging to Group VIII of the periodic table with an organic compound of phosphorus, arsenic, antimony or bismuth are known. However, these methods have disadvantages in that reaction must be carried out at a relatively high temperature and yield of desired product may decrease due to catalyst employed.
Recently, another method using palladium black and an alkyl halide or a hydrogen halide as a catalyst has been developed. However, this method also has disadvantages in that inactivation of catalyst occurs rapidly, inpurities such as allene act as inhibitors for the reaction, and satisfactory selectivity cannot be obtained.